First things first...why does one purchase airline conforming sized carry-on luggage to begin with? My humble opinion is convenience, travel light, and no baggage claim fiascos. AA often asks for volunteers to check their carry-on, then typically forces non-volunteers until the luggage goal is obtained. Over all these years of flight, an airline can't do the math & measurements as to what,who,and how things will fit? Baffles me. Other than choosing the almighty dollar over customer satisfaction!
Secondly, let's talk about delays. This subject seems to be all too common on this forum. 4 flights, 4 delays in the past month with American Airlines. Wierd how I haven't had any delays with Southwest or United in the past year of travel. I was an aircraft mechanic for 16 years and in aviation management for another 5. So I understand the business and unpredictable discrepancies, malfunctions, weather, etc. But come on! I suggest an audit, because the process seems to be broken with little concern for necessary improvement.
On the upside, the gate employee was amazingly kind and understanding (carry-on issue at BWI). I would give her 5 stars.
I'm done traveling with AA. If you have a choice and want a lower risk of delays and misfortune, you should probably go with a more reliable airline.